Electrode for arc-lamps.



uNItrE-n srATEsPAT NT oFFroE.

JOHN T. H. DEMPsTnn, CF-SCI-IENECTADY, NEW YORK, AssIGNoR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

nrno'raonn FOR. zine-LA PS;

1,010,402. No ,Drawingq To all 107mm it may concern.

Be it known that I, JOHN T. H. DEMrarea, a citizen of the United States, residing at Schenectady, county of Schenectady,

State of New York, have invented certain new and useful Improvements in Electrodes for Arc-Lamps, of which the following is a.

luminous and highly efiicient arcs'I.

.In carryingout myinvent-ion I form a. mixture containingtitanium, preferably in the formof one or more of its oxids, with some comparatively good conducting m'etal-. 11c material which, preferably, also gives a luminous are, such as iron, which may also be in the form of one or mor of its oxids.

To this mixture I may add a small quantity of some substance such as boric aicid; potassium carbonate or the like, which serves as a fluxfor the other materials in the electrode'.

'The materials above mentioned, or their equivalents, may be combined in various proportions and electrodes formed from the combination in various ways to obtain highly desirable results.

In particular I have found that an excel lentform of the electrode can be produced,

in the following manner: A mixture contaming- 160. parts of the magnetic oxid of iron, 40 parts of the red oxid of iron, 1-5

parts of rut-ile and 1 part of boric acid is. .35

-' in a powdered condition, To this mixture enough water, containingpreferably about first formed, the various constituents being 5 per centof glycerin, is added to render the mixtureabout as fluid as paint. The mixture is then thoroughly worked to gether, as by grinding it in a paint mill for several hours; at the ,end'of that time the mixture is heated and enough water is driven off to give the mixti'ire about the consistency ofhard putty. Pencils or the like are-then formed from the mixture by molding it or forcing it through dies. The

red oxid of iron added to the mixture in the. -proportio-ns above stated is advantageous, as its presence renders the plastic mass easier to mold or press into pencils.

The pencils are first brought gradually up to the temperature of about 200 degrees C., in a drying oven or the like. This heating drives oil; the remainder of Specification of Letters Patent. Application 'filecl llecember 10, 1903. Serial No. 184,662.

although the use of. a

the moisture.

atented Nov. 28, 1911.

frbm'the pencils. The glycerin in the water seems to decrease the rate of evaporation, which results in a more even drying throughout the body of the electrode than would otherwise be the case and thereby'tends to minimize the liability of distortion or crackingof the pencils. After all the moisture is driven out of the pencils in the preliminary baking operation'at .t-he

-comp? 1ratively low temperature specified, the pencils sufi'erlittle, if any, distortion in;

shapeby the baking operation from which they come out in the form of dense, hard,

homogeneous sticks.

The'pencils formed in the manner hereinbefore described possess excellent light giv ing qualities. The presence of titanium oxid or -'oxids, by virtue of their titanium content, insures a luminous are from which a large amount of white light radiate s. The presence of theiron oxid adds much to the steadiness of the-arc, and by reason of its metallic characteristics, to theconductivity oft-he electrode.

p the drying'operation the pencils arebaked. "In the baking W'hle the high efficiency of the electrodes results largely from the luminosity of the titanium in the are it should be noted that the iron which enters the are also gives luminosity tothe same, the are spectrum showing a predominance of the lines .due to both titanium and iron.

The conductivity of the electrodes may be increased by incasin'g the pencils in thin shells of some metal, which is preferably iron. My invention, however. is not confined to this particular means for increasing the electricconductivity of the electrodes,

metal shell, and particularly of an iron shell, is my preferred for instance, the porosity of the electrodes is means for accomplishing this result; thus,

tivity increased by prolonging the period during which they are heated to a temperature which'will cause a flowing together'of the particles composing the electrodes.

The preparation of an electrode containing comparatively large amounts of metallic material which, in its ordinary form, is a good conductor of heat and electricity, in such a manner that the best heat conductivity of the electrode is comparatively poor 7 may be quite desirable for some purpose, namely, for the purpose of maintaining the arcing end at a high temperature, whereby the electrode is consumed more evenly across its end surface. Obviously this feature of my invention is not limited to the materials specified.

Instead of forming the electrodes from an artificialq mixture of titanium oxid and one or more'of the oxids of iron I may employ natural titaniferous magnetite in which titanium oxid and iron oxid are combined in suitable proportions. In 'the natural titaniferous magnetite the titanium and iron are very intimately combined and very homogeneous electrodes can therefore be formed from it. When I employ natural titaniferous magnetite as the material out of which I make electrodes I usually find it necessary or, at least, desirable to purify it, particularly by removing more or less of the silicates .which are usually found in it. The purification may be carried on in various ways known to those skilled in the art.

While I have described in detail electrodes formed in a manner and from materials proportioned to give highly advantageous results I do not intend that my invention in all its aspects shall be limited to the proportions or method given. In particular I found that the proportions of oxids of iron and titanium in the mixture from which the stick is made can be varied considerably; for instance, I have obtained very good results with electrodes in which substantially equal amounts of the iron and titanium oxids are employed. I

In the foregoing description I use the Word metallic as signifying a substance containing or having the characteristics of a metal, which produces an are which is very diiferent from the arcs produced by non-metallic electrodes, such, for example, as carbon electrodes.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A metallic are light electrode yielding an arc in whose spectrum titanium and iron lines predominate.

2. A metallic are light electrode, conducting at ordinary temperatures, containing titanium oxid.

3. A ferruginous are light electrode, conducting atordinary temperatures, contain-.

ing titanium oxid.

4. An are light electrode composed principally of a mixture of titanium'oxid with ferruginous material.

5. A ferruginous are light electrode conductin at ordinary temperatures containingatIe 6. A metallic are light electrode comprising a preponderating amount of ferruginous and titanic materials.

7. An are light electrode composed principally of oxide of iron and titanium.

S. A metallic are light electrode containing iron oxid, titanium oxid, and a flux therefor.

9. An are light electrode composed principally of natural titaniferous magnetite.

10. An are light electrode composed principally of purified natural titaniferous magnetite. I

11. An are light electrode containing a mixture composed principally of oxids of iron and titanium of which the titanium oxid forms at least seven per cent. of the whole. 7

12. An are light electrode composed principally of a mixture of titanium oxid with some comparatively good conducting metallic material which in consuming gives a luminous or flaming are.

13. An are light electrode composed principally of a mixture of titanium oxid with some refractory not readily oxidized material which in consuming gives a flaming or luminous are.

14:. A metallic are light electrode consisting of an iron shell filled with a mixture containing iron oxid and titanium oxid.

15. An are light electrode composed principally of titanium oxid, iron oxid and iron.

16. An are light electrode composed esast seven per cent. oftitanium oxid.-

sentially of iron and compounds of iron and titanium yielding an arc in the spectrum of which the iron and titanium lines predominate.

. 18. An are light electrode metallic in composition containing titanium oxid.

19. An are light electrode composed principally of a mixture of titanium oxid with a metallic substance having greater electric conductivity than said oxid.

20. An are light electrode having as its principal constituents iron, titanium and oxygen.

21. An are light electrode composed principally of a natural combination of iron, titanium and oxygen.

22. An arc light electrode metallic in composition and conducting at ordinary temperatures, containing not less than seven per cent. of titanium oxid.

23. An arc light electrode composed principallyof a mixture of titanium oxid with a metallic material.

24. An are light electrode composed lat ely of a mixture of compounds of iron In witness whereof, I have hereunto set an 'tltanium yielding an arc in the 'specmy hand this 7th day of December 1903. trum of which the iron and titanium lines predpminawh JOHN'T, H. DEMPSTER. 5 25. An ,arc li%ht. electrode composed Witnesses: largely of a meta licoonducting substance BENJAMIN B. HULL,

conglomerated witha titanium compound. MARGARET E. WOOLLEY. 

